Soft drinks giants such as Coca-Cola and PepsiCo have pledged they will cut sugar levels in their products ahead of a British government’s plan to levy a sugar tax.

The companies say they will introduce a series of “unprecedented” measures of their own volition, which they claim will help reduce Britain’s sugar consumption by a fifth.

The measures include not targeting children under 16 in their advertising as well as introducing smaller, healthier products.

However, Coca-Cola is said to be sticking to its sugar levels.

The move comes just days before the British Prime Minister, David Cameron is to decide whether to go ahead with plans for a controversial sugar tax to address what medical experts have described as a time bomb of childhood obesity.

The British government is planning to place a 20 per cent sugar tax on soft drinks and processed foods which contain high sugar levels, to raise up to £1bn a year.

Kellogs, maker of breakfast cereals has already pledged to cut 723 tons of sugar next year from its cereals, while the makers of Lucozade and Ribena are aiming to cut sugar levels 10 per cent by 2018, and 20 per cent by 2025 or sooner.

Other soft drink giants like Pepsi and Britvic will ban TV adverts targeting children and billboards near schools.

Smaller sizes and new healthier products are also planned.

Coca-Cola which had also signed on to the industry-wide pledge to cut sugar levels to 20 per cent by 2020 said it is only promising another five per cent over the next five years. Coca-Cola had cut calories in its drinks by five per cent in 2014.

Anti-sugar campaigners in Britain such as chef Jamie Oliver, have led calls for sugar tax to reduce childhood obesity.

However, industry stakeholders claim they are being scapegoated as 57 percent of soft drinks sold in Britain are low or no-calorie. They claim that soft drinks are responsible for only the fifth biggest source of sugar in a family diet, below milk and cream.

Meanwhile, data from a research consulting firm, Kantar show that the largest proportion of sugar in a family diet, (15%) comes from fruit and vegetables, with packet sugar responsible for the second largest amount.